This thesis explored emotion recognition and emotion expression in people with anorexia nervosa (AN) and bulimia nervosa (AN), compared to a matched healthy control group. It includes a set of distinct, but interrelated studies, which are described in two chapters, one for emotion recognition, and one for emotion expression. The broad hypothesis was that participants with eating disorders (ED) were less accurate recognising emotions and less facially expressive than HC. Studies investigating emotion recognition: Study 3.1 evaluated the ability to recognise emotions in blended facial expressions in adult women with AN (n=35), compared to HC (n=42). Participants with AN showed difficulties recognising disgust, and a preference to label non-angry facial expressions as anger. Study 3.2 assessed emotion recognition through body movement in adolescents and adults with AN (n=97), compared to HC (n=96). Results indicated that participants with AN had difficulties recognising sadness, often misinterpreting it as a neutral emotion. Adolescent participants with AN had worse performance. Study 3.3 investigated emotion recognition from facial expression and body movement in women with BN (n=26), compared to HC (n=42). Findings were similar to those of study 3.1, with BN participants having difficulties in disgust recognition, and showing a bias towards anger. Studies investigating emotion expression: Study 4.1 assessed facial expressions of positive emotions in people with AN (n=20), BN (n=20), and HC (n=20), through an examination of the Duchenne smile expressed in response to a humorous film clip. The study results showed a reduced facial expression of positive emotions in people with AN. Study 4.2 investigated facial expression of negative emotions in people with AN (n=20) and BN (n=20) compared to HC (n=20), by looking at expressions of sadness and other negative emotions in response to a sad film clip. There was no evidence of reduced facial expression in the ED group. Study 4.3 explored the ability to deliberately generate (i.e. pose) and imitate facial expressions of emotions in a group of participants with AN (n=36), BN (n=25), and HC (n=42). Results revealed that both ED groups were less accurate than the HC group at posing facial expressions of emotions, and participants with AN had difficulties imitating facial expressions of emotions. Overall, the findings provide evidence of difficulties in emotion processing in people with ED, especially reduced facial expression of emotion. The findings suggest that emotion recognition is more preserved, but there might be specific problems in the processing of disgust and anger. In general, participants with AN had more difficulties than those with BN. The thesis findings provide support for emotional maintenance models of ED, and may inform the development of future treatments.